/*
   *   Copyright (C) Tino Reichardt, 2012
   *
   *   This program is free software;  you can redistribute it and/or modify
   *   it under the terms of the GNU General Public License as published by
   *   the Free Software Foundation; either version 2 of the License, or
   *   (at your option) any later version.
   *
   *   This program is distributed in the hope that it will be useful,
   *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
   *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
   *   the GNU General Public License for more details.
   *
   *   You should have received a copy of the GNU General Public License
   *   along with this program;  if not, write to the Free Software
   *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
   */
  
  #include <linux/fs.h>
  #include <linux/slab.h>
  #include <linux/blkdev.h>
  
  #include "jfs_incore.h"
  #include "jfs_superblock.h"
  #include "jfs_discard.h"
  #include "jfs_dmap.h"
  #include "jfs_debug.h"
  
  
  /*
   * NAME:	jfs_issue_discard()
   *
   * FUNCTION:	TRIM the specified block range on device, if supported
   *
   * PARAMETERS:
   *	ip	- pointer to in-core inode
   *	blkno	- starting block number to be trimmed (0..N)
   *	nblocks	- number of blocks to be trimmed
   *
   * RETURN VALUES:
   *	none
   *
   * serialization: IREAD_LOCK(ipbmap) held on entry/exit;
   */
  void jfs_issue_discard(struct inode *ip, u64 blkno, u64 nblocks)
  {
  	struct super_block *sb = ip->i_sb;
  	int r = 0;
  
  	r = sb_issue_discard(sb, blkno, nblocks, GFP_NOFS, 0);
  	if (unlikely(r != 0)) {
  		jfs_err("JFS: sb_issue_discard" \
  			"(%p, %llu, %llu, GFP_NOFS, 0) = %d => failed!
  ",
  			sb, (unsigned long long)blkno,
  			(unsigned long long)nblocks, r);
  	}
  
  	jfs_info("JFS: sb_issue_discard" \
  		"(%p, %llu, %llu, GFP_NOFS, 0) = %d
  ",
  		sb, (unsigned long long)blkno,
  		(unsigned long long)nblocks, r);
  
  	return;
  }
  
  /*
   * NAME:	jfs_ioc_trim()
   *
   * FUNCTION:	attempt to discard (TRIM) all free blocks from the
   *              filesystem.
   *
   * PARAMETERS:
   *	ip	- pointer to in-core inode;
   *	range	- the range, given by user space
   *
   * RETURN VALUES:
   *	0	- success
   *	-EIO	- i/o error
   */
  int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range)
  {
  	struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
  	struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
  	struct super_block *sb = ipbmap->i_sb;
  	int agno, agno_end;
  	u64 start, end, minlen;
  	u64 trimmed = 0;
  
  	/**
  	 * convert byte values to block size of filesystem:
  	 * start:	First Byte to trim
  	 * len:		number of Bytes to trim from start
  	 * minlen:	minimum extent length in Bytes
  	 */
  	start = range->start >> sb->s_blocksize_bits;
  	end = start + (range->len >> sb->s_blocksize_bits) - 1;
  	minlen = range->minlen >> sb->s_blocksize_bits;
  	if (minlen == 0)
  		minlen = 1;
  
  	if (minlen > bmp->db_agsize ||
  	    start >= bmp->db_mapsize ||
  	    range->len < sb->s_blocksize)
  		return -EINVAL;
  
  	if (end >= bmp->db_mapsize)
  		end = bmp->db_mapsize - 1;
  
  	/**
  	 * we trim all ag's within the range
  	 */
  	agno = BLKTOAG(start, JFS_SBI(ip->i_sb));
  	agno_end = BLKTOAG(end, JFS_SBI(ip->i_sb));
  	while (agno <= agno_end) {
  		trimmed += dbDiscardAG(ip, agno, minlen);
  		agno++;
  	}
  	range->len = trimmed << sb->s_blocksize_bits;
  
  	return 0;
  }